1. Field of the Invention
In general, the present invention relates to a playback apparatus and a playback method. In particular, the present invention relates to a playback apparatus and a playback method wherein, in the case of a movement of an optical pickup with servo control of a driving unit thereof put in a halted state or in the case of a movement of the optical pickup from a read position to another over a long distance, if the track to be read next is within a predetermined distance from an edge of an area for recording data, the distance of movement of the optical pickup from the present read position to the destination of the movement is set at a value shorter than the actual distance from the current read position to the track to be read next.
2. Description of the Related Art
At the present time, an optical disk such as a compact disk for recording digital data is becoming popular. In the case of such an optical disk, data is recorded on tracks formed in the circumferential direction of the disk.
In an operation to play back data recorded on an optical disk, an optical pickup is used for radiating a laser beam to pits which are formed on each track of the optical disk to form a shape representing data recorded on the track. A light reflected by the pits is then converted into an electrical signal representing the data.
Driven by typically a thread motor, the optical pickup moves in a direction perpendicular to the tangential direction of the tracks of the optical disk, that is, in the radial direction of the disk. Thus, in an operation to read out data recorded in a noncontiguous region, a control circuit for controlling the thread motor computes the number of tracks to skip in order to go to the next track having a sector to be read next from a sector address representing the present read position and the address of the sector to be read next. The optical pickup is then driven to move (or driven to make a track jump) over as many tracks as computed by the control circuit.
In order to complete a change from the present read position to a next one in a short period of time in a movement of the optical pickup over a long distance, for example, the playback apparatus moves the pickup by putting the tracking servo in a halted state.
If a track jump is made by putting the tracking servo in a halted state as described above, however, it is quite within the bounds of possibility that an error is generated in the movement distance of the optical pickup. That is to say, the optical pickup may be moved in a track jump to a next position separated away from the movement destination by an error A of the track jump. Normally, the distance T from the present position of the optical disk to the destination of a track jump is expressed in terms of tracks, where T is the number of tracks representing the distance from the present position to the destination. In the case of a track jump toward the circumference of a data area, the error A may have such a large value that the destination is located within a distance to the edge of the data area which is shorter than the error A as shown in FIG. 4. In such case, it is quite within the bounds of possibility that the optical pickup is moved to a location outside the data area, giving rise to a problem that it is hard to reproduce data from the optical disk due to a difficulty to carry out servo control.